How do i solve this problem step by step i can get only so far 2x to the second power equals -9x + 15

An automobile assembly line operation has a scheduled mean completion time, μ, of 12 minutes. the standard deviation of completion times is 1.6 minutes. it is claimed that, under new management, the mean completion time has decreased. to test this claim, a random sample of 33 completion times under new management was taken. the sample had a mean of 11.2 minutes. assume that the population is normally distributed. can we support, at the 0.05 level of significance, the claim that the mean completion time has decreased under new management? assume that the standard deviation of completion times has not changed.

Jimmy can run 3.5 miles in 20 minutes. how far can ne run in one hour and ten minutes?

There are 93 calories in a small candy bar how many calories are ther in a half dozen small candy bars?